The characteristics of an inductor are dependent on the current and voltage source excitation signal, wave shape, and frequency of operation, which may vary in real time operating conditions. Inductance measuring devices typically utilize simulation techniques, such as subjecting the inductor to a known excitation signal having a controlled current and voltage source, wave shape, and frequency of operation to measure the inductance.
One type of inductance measuring device is a multifunction meter, such as an inductance/capacitance/resistance (LCR) meter. The LCR meter uses a principle of a balancing bridge or an auto balancing bridge. The measurement device excites the inductor using built-in signal generator and bridge balancing technique to measure the value of impedance of the inductor. Specifically, in an LCR meter, the signal source is a sinusoidal wave, whereas in a real operating environment, the signal may be a square wave with a high voltage and a high current component.
However, real operating signals are dependent on the wave-shape, excitation level, and operating frequency of the source, as well as the external factors from other circuit elements and the surrounding environment. Therefore, it is desirable for power supply designers and others to be able to measure and observe the behavior of an inductor in a dynamically changing environment of a power supply.
One technique for measuring inductance under a real time environment is by calculating the slope of the B-H curve (where B is magnetic flux and H is the magnetizing current). Plotting the B-H curve and measuring the slope of the curve is a complex process, since each step requires careful and correct manual analysis.
The B-H curve may be plotted in a digital storage oscilloscope (DSO) that supports XY display mode. However, a user must provide correct signals to the DSO. Specifically, generating the B signal requires an external hardware circuit that integrates the voltage with a known time constant (√Vdt), which represents the magnetic flux B.
Currently, none of the digital storage oscilloscopes available in the market have a scope resident feature capable of analyzing the plot data and giving the results extracted from the plot. Therefore, there is a need in the art for a digital storage oscilloscope having built-in capabilities for observing the behavior of the inductor in a dynamically changing (real-time) operating environment.